Nausea and emesis are often induced by stimulation of either the chemoreceptor trigger zone or the emesis (or vomiting) center in the central nervous system. Such stimulation can be caused by afferent stimulation (e.g., tactile pharyngeal impulses, labrynthine disturbances, motion, increased intracranial pressure, pain, distention of viscera or psychologic factors) or blood born emetic substances (e.g., as seen during pregnancy, cancer chemotherapy, uremia, radiation therapy, electrolyte and endocrine disturbances, or the presence of chemical emetic substances). Nausea and vomiting are also common post-operative side effects that result from the use of anesthetics. These symptoms are known as post-operative nausea and vomiting (PONV).
A series of medication alternatives are currently used to combat PONV. The drugs used most frequently are benzamides (e.g. Metoclopramide),phenothiazines(e.g. Phenergan) and Serotonin inhibitors (e.g. Ondancetron). In order to minimize the side effects, these drugs are most often administered in this sequence. If Metroclopramide fails to produce adequate relief, Phenergan is administered. If sufficient relief is still not experienced, Ondancetron is given to the patient. In efforts to control cost and potential side effects, these medications are usually given in sequence at 30 minute intervals. This methodology can significantly prolong the time the patient remains in the recovery room, an area of the hospital where every additional minute represents enormous expense.
The most common side effects of metroclopramide, which are experienced by about 10% of treated patients involve the central nervous system (CNS) and include restlessness, fatigue, drowsiness and lassitude. Insomnia, headache and dizziness occur less frequently. Delirium, severe dysphoria, obsessive rumination, mania, depression, and suicidal indication have also been reported. Extrapyramidal effects also result from dopaminergic blockage. This usually presents in the form of akathisia and occurs most often in children and young adults. Dystonic reactions resembling acute dyskinesia occur in less than 1% of young patients receiving low doses of Metroclopramide, but occur as often as in 25% of patients receiving higher doses.
Phenergan (a phenothiazine derivative) is frequently the second line drug for treating PONV. In addition to producing all the side effects of other antihistamines, phenothiazines have their own side effects. These stem in part from the anticholinergic effects of the drug and include dry mouth, blurred vision, confusion and delirium. Extrapyramidal side effects include lassitude, inco-ordination, tinnitus, diplopia, excitation, nervousness, seizure and catatonia. Bradycardia and hypotension have also been reported with rapid intravenous administration. Promethazine is a chemical irritant and extravasation has resulted in necrotic lesions. Venous thrombosis is an additional potential side effect.
The serotonin inhibitors represent a new class of anti-emetics that are normally well tolerated by most patients. Studies comparing the incidence of the side effects of Ondancetron vs. Metoclopramide indicate that Ondancetron produces a higher incidence of headache (17.25%) and constipation (3%), while Metoclopramide produces diarrhea and extrapyramidal symptoms more frequently. Twelve percent of patients who were administered Ondancetron for PONV complained of dizziness, 8% complained of sedation and drowsiness, 5% complained of malaise or fatigue and 2% complained of paresthesia. Pruritus has been reported in 2% of patients receiving Ondancetron. Hypersensitivity reactions typically occur when repeated dosages are administered in efforts to control PONV. Cardiovascular side effects are rare but when experienced are serious and usually occur at dosages used for chemotherapy induced nausea and vomiting.
Droperidol is sometimes used for PONV and can be quite effective. Unfortunately, the use of this drug tends to significantly prolong the recovery room stay due to the associated excessive sedation. The drug can produce profound dysphoria. Extrapyramidal effects have also been reported with some regularity.
The plethora of drugs that are used in efforts to treat PONV demonstrates their relative ineffectiveness in producing relief. The serotonin inhibitors while being more effective, unfortunately remain expensive. In addition, patients who are experiencing PONV usually have IV access. These medications are typically given parenterally to insure delivery and to hasten their onset. Hence, they share the risks associated with any parenteral drug, such as error, infection, overdose, extravasation, in addition to the added expense.
In summary, the drugs currently being used to treat PONV are often ineffective and can ultimately demand the use of all three types of medications, produce undesirable and in some cases high risk side effects, require administration by skilled nursing personnel (an added expense), significantly increase the time patients remain in the recovery room, and are themselves expensive.
Anti-emetic devices that are specifically designed to easily, safely, and efficiently administer alcohol to a person have not been previously disclosed or suggested.